In an article entitled "A New N-Way Power Divider/Combiner Suitable for High Power Applications", published in the MIT Symposium Digest, 1975, pp. 116-118, the author, Ulrich H. Gysel, discloses a microwave circuit (assumed to be a combiner circuit), which avoids the presence of extraneous signals that may flow reversely through ports and averts other detrimental electrical effects. The microwave circuit includes circuit boards and transmission lines which are all in the form of strip lines printed on such boards except that one such line is a coaxial line. In such a circuit, a primary port is connected by a coaxial line Z1 to a Junction to which are also connected a number of strip lines Z2 connected at their ends away from such junction to such corresponding secondary ports. The lines Z2 provide principal paths for transfer of microwave signals between the secondary ports and the mentioned junction.
In order for a signal received at any one secondary port to reach, through principal paths, any other secondary port as an extraneous signal, that signal must travel through two principal paths, a distance between those two ports, which is a half wavelength of the microwave signal at the mid frequency of the combiner. Such extraneous signal undergoes approximately a 180.degree. phase shift in the course of such travel. The author reduces the presence of such extraneous signals at the secondary ports by respectively connecting these ports to a number of supplemental signal transfer paths, each composed of a strip line Z3 and a strip line Z4 in series, and all connected to a common floating point at their ends away from the secondary ports. Each such supplemental path has a length of one half wavelength. This causes extraneous signals to pass through not only two principal paths but also through two supplemental paths. The fraction of the signal which travels through the supplemental paths to the destination port undergoes a phase shift of 360.degree. and becomes exactly out of phase with the fraction of the extraneous signal reaching the port through the two principal paths. These two signal fractions then cancel each other so as to reduce the resulting extraneous signals to low levels.
The Gysel arrangement exhibits the disadvantage of requiring several impedance coaxial transmission lines.